Automatic telephones are well-known which have dials which are provided with a mechanical, rotary finger-plate for dialing a number to be called, i.e., the prior art dials of automatic telephones are nearly exclusively of a mechanical and rotary type for dialing a number. The dials have a mechanical delay after which the telephone number must be dialed when the line is engaged.
To improve the operative features of a telephone having such a prior art dial, some solutions have been proposed and tried. For example, the use of mechanical means has been proposed to overcome the supply delay, and electromagnetic means have been employed to open and close the telephone line at the moment pulses are sent thereon. Some drawbacks have, however, been found which are connected with these proposed improvements, for example, the different set-up caused by the influence of the elastic characteristics of the materials being used for a mechanical delay, or rod jamming of the relays being employed in electromagnetic devices, or further need of a well-defined position of the telephone apparatus or some parts of same when devices with mercury wetted contacts are employed.
The application of electronic circuits has also been tried. At present these solutions to a telephone apparatus are less than desirable since the circuits must be specifically designed and manufactured in its entirety, i.e., both the dialing device and the telephone case with its electrical circuits must be changed in respect to a conventional telephone, while the substitution of an improved electronic dial only for a conventional dial of the mechanical rotary type has not yet been considered.
It will be understood that such a substitution is really very important because of the actual enormous distribution of automatic telephones. For the same reason the keyboard control system for dialing a telephone number, while pertaining to these electronics solutions of the problem, could not previously be considered satisfactory by itself, if a large production of same is desired.
Referring to the visible display of a called number, it is further pointed out that such a feature is very important in a telephone when the called number is displayed as the keys relating to the component digits thereof are sequentially depressed by the user, or as the correct selection sequence of said component digits occurs at the telephone exchange. In accordance with the above considerations, such a feature may also be very important when the visible display device is a part of the dial wherein the electronic circuit systems are included for the operation of the telephone.
It will be understood, by those skilled in the art, that through inattention and/or wrong operation of the telephone apparatus, a number may be dialed which is different from the number to be called. Thus, not only with the caller have an actual loss of money due to the wrong telephone call, such a loss being as great as the distance to the called subscriber by direct dialing increases, but there is also time loss for both telephone users, the former of which needs to dial again the number. On the other hand, in accordance with known techniques, the exactitude of a dialed number could until now only be controlled through a confirmation which is phonically received by the called subscriber.